At least 260 migrants have reportedly been injured in clashes at the Greece-Macedonia border, according to medical reports. Police deployed tear gas against asylum seekers as they attempted to cross the border.

Dozens of people were injured in incidents in Greece on the border with Macedonia on Sunday, AFP reported, citing Medecins Sans Frontiers (Doctors Without Borders). The humanitarian aid organization said it had sent additional teams to help migrants at the Idomeni refugee camp.

People were treated by MSF medical units mainly for breathing problems, but also for other injuries, including some caused by plastic bullets, MSF official Achilleas Tzemos told AFP. A pregnant woman was among the victims, MSF said, adding that its staff have also been affected.

At least 15 police officers were injured in the clashes, five of them seriously, Balkan Newsbeat reported. Many police vehicles and other equipment were damaged by stones thrown by the migrants, the report added, saying that reinforcements will be posted throughout the camp overnight.

A Ruptly crew covering the migrant crisis in Idomeni said they were caught in the clashes and were teargassed.

Ruptly journalist Katica Djurovic said that police also deployed stun grenades against the asylum seekers.

According to the Greek newspaper Antenna, a group of asylum seekers attempted to cross the border and enter Macedonia, with Macedonian police then responding with tear gas and stun grenades.

“I was teargassed at least twice. Not just me, another cameraman, other press people were also teargassed as well as refugees. Some of the tear gas [was] thrown at least 200 meters into the camp, into the tents where most of women and children were sitting.”

“They [asylum seekers] threw rocks at the Macedonian police. The police fired tear gas in response," a Macedonian official told Reuters on condition of anonymity. “The migrants were pushing against the fence but standing on the Greek side of the border. The fence is still there, they have not broken through.”

The Greek authorities have condemned the “indiscriminate” force being used against asylum seekers by Macedonian officers.

"The indiscriminate use of chemicals, rubber bullets and stun grenades against vulnerable populations, and particularly without reasons for such force, is a dangerous and deplorable act," said George Kyritsis, a spokesman for migration coordinators in the Greek government, as cited by Reuters.

In March, the EU reached a deal with Ankara which will see all illegal migrants reaching Greece from Turkey sent back. In return, the EU will take in thousands of Syrian refugees directly from Turkey.

The EU continues to face the biggest refugee crisis since 1945. More than one million asylum seekers entered Europe in 2015, most of them from Syria, where a civil war has taken the lives of 250,000 people and displaced 12 million since 2011, according to UN figures.